The invention is particularly suited for use in AR 15 type semi-automatic firearms but with minor physical modifications could be more widely usable. The closest prior art is U.S. Pat. No. 5,501,134 issued Mar. 26, 1996 to Milazzo et al. specifically for AR 15 or M 16 type firearms. The invention is similar to Milazzo in that both use essentially a two stage trigger pull. In both the second stage of the trigger pull is adjusted to have minimal engagement between the engagement means of the hammer and trigger thereby allowing very limited second stage pull on the trigger to fire the gun. However the invention does have important differences from Milazzo. The difference are of major importance to match shooters. In Milazzo and prior art the first stage pull pressure of the trigger can only be adjusted by replacing or bending the trigger spring furnishing the pressure. The user must essentially dismantle the trigger mechanism to make this change. This is quite different than the user adjustable trigger spring loading of the subject invention wherein the trigger spring adjustment may be made without disturbing the overall assembly.
In Milazzo a disconnector pivotally connected with the trigger at one end and spring loaded on the other with a single screw compressing a spring is used to adjust the length of the contact face to achieve minimal engagement of the engagement means engaging the hammer with the trigger at the point trigger movement moves a contact face on the disconnector against a hammer tang on the hammer. Necessarily in Milazzo as the single adjustment screw is tightened to achieve minimal engagement of the hammer with the trigger the spring is being compressed and the pressure of the contact face against the hammer tang is increased thereby requiring a greater pull pressure on the second stage trigger pull to fire the gun. Any one spring can be chosen to give one set pull pressure and, of course different springs could be used to achieve different pull pressures. However changing the springs would require essentially dismantling the trigger assembly. This is in contrast with the subject invention wherein a disconnect lever pivoted in the center on a pivot pin and operably connected with the trigger uses one user adjustable screw on one end to set the minimum engagement of the engagement means engaging the trigger and the hammer before the user reaches the second stage pull and a second screw on the opposite end of the disconnector lever adjusts pressure on a spring and is in a position so that the user may easily tighten or loosen the screw to adjust pressure of the contact face of the disconnector against the hammer tang thereby adjusting pressure needed on the second stage pull to fire the gun. With the feature of the invention as outlined a match shooter may readily adjust both second stage travel and second stage pull pressure and may also easily adjust first stage pull pressure while still maintaining the desirable full engagement of the faces of the hammer and trigger engagement means with the firearm or gun in the cocked position.
Other features of the invention are known in the art.